The strain of exertion in this rarefied air brought about a painful incident. Exhausted from cold and fatigue, a man called Rubso, a Christian convert, was seized with cramp. He was lying in a semi-conscious state, his teeth chattering, his features distorted and livid; his eyes were sunken and lifeless. We carried him under the shelter of a rock and rubbed him vigorously, endeavoring to restore his circulation. He eventually recovered enough to come along. From our high point we now had to descend to the pass six hundred feet lower. We made our way along dangerous rocks and debris. I was clinging, with half-frozen fingers, to a prominent rock when I heard screams of distress from below. On the steep incline of snow two coolies, with their respective loads, having lost their footing, were sliding at an incredible speed. They finally reached the bottom of the basin, where the change in the descent made them turn involuntary somersaults, while their loads flew off in every direction. I was relieved when I saw the men getting up again. One of them staggered, and fell back a second time as if dead. Hastening over the slippery rocks, and then down over loose stones, I reached the pass. This was 18,150 feet above the sea. Two reluctant men were sent to the relief of the coolie in distress. He and his load were at last carried up to the place where I was. He had been badly shaken and was aching all over, but was able to continue with us. We hurried down the steep slope on the Tibetan side, to get away quickly from the bitterly cold, windy pass. Describing a wide curve, and then across several long snow-beds, we at last reached the river-level, and pitched our tents on snow at an elevation of 16,900 feet. There was no wood; no yak or pony dung, no lichens, no moss, and therefore nothing with which we could make a fire. My men believed that eating cold food at high elevations, when the temperature was low, led to certain death. They preferred to remain without food altogether. Night came, and with it the wind blowing in gusts, and piling the grit and snow around our tents. In the night, when a hurricane was raging, we had to turn out of our flapping canvasses several times to make the loosened pegs firmer. Refastening the frozen ropes was icy-cold work. At 2 A.M. the thermometer was down to 12 deg.; at 9 A.M., in the sun, it went up to 26 deg., and inside the tent at the same hour we had a temperature of 32 deg.--freezing-point.